I've done some research on this issue and, while I've seen somewhat similar reports, they usually seem to be a little different so I thought I would get everyone's opinion.
Current Zimbra Version: 7.1.3_GA_3346
Steps to Reproduce
- Share your calendar with someone
- Have them add an event to your calendar
- Once the event has synced to the phone, have them remove or move the event
Your calendar will still show the old event, not remove/move it, and no longer sync your calendar. Going in to Settings -> Accounts & Sync shows a generic Unknown Server Error as the reason for the failed calendar syncs. Mail and contacts still sync without issue. This occurs in both VZA and standard ActiveSync Mail setup, and has been reproduced on an HTC Hero, HTC Thunderbolt, and a Droid Incredible.
The only way I've found that will get calendars to start syncing again is to completely delete and re-add the account.
This has become a big issue at my company because of the number of users that rely on their phone to view their calendar. I'm not sure if it will be very helpful, but I've attached a ZCS log file of the time the shared event was added and removed and when the failed syncs began. Any input would be greatly appreciated.